孟加拉采购需求：奥努，奥努埃彭，奥努Gpon，埃彭奥努，Gpon Onu，Gepon Onu

I am reaching out for some technical assistance regarding an issue I'm facing with changing the default gateway on the OLT device. When I attempt to execute the command to set the default gateway, I receive an error message indicating that the operation failed. Specifically, the command I am trying to run is "route default gw 10.100.100.21," but I keep encountering the error: "Route default gateway set fail, reason: delete route default gateway failed." This issue is critical for my ongoing work, and I need guidance on how to resolve it effectively. Any insights or step-by-step instructions you can provide would be greatly appreciated. If there are specific troubleshooting steps or configurations I should consider, please include those as well. Your support in this matter would be invaluable.